Although the marketing of particulate detergent compositions packaged in cartons is common practice, this imposes constraints both on their formulation and methods of production. For example the compositions must be free flowing and have an attractive appearance to the consumer, and the ingredients should not segregate during transport and storage. The products must also be safe, both for contact with the skin and in the event of accidental ingestion; in particular, the compositions should not contain too high a level of alkaline materials, although alkalinity is beneficial for detergent properties.
When using washing machines which have a rotating drum in which the fabrics are placed, there can also be substantial losses of conventionally dosed detergent powder by retention in the dispenser and by its accumulation in the dead spaces beneath the drum, such as the drain hose.
It has been proposed previously to market powdered detergent compositions in packages, each of which contain suitable amounts of the detergent powders for individual washes under standard washing conditions. In particular, from British Pat. No. 1,298,454 and U.S. Pat. No. 3,198,740 the detergent powders can be contained within bags of water-permeable or water-soluble materials, such as soluble polyvinyl alcohol, but such packages have not yet met with much commercial success. One of the reasons for this, in the case of water-soluble bags, is the sensitivity to moisture which leads to storage difficulties. In the case of water-permeable materials, one of the reasons is the difficulty of making the bags sufficiently permeable to water in use so that the contents of the bags are rapidly dissolved out into the wash liquor, and yet reducing dusting of the detergent powder out of the bags during transport and manual handling to an acceptable level. Also, some detergent compositions, in particular bleach-containing compositions, cause inacceptable degradation of the bag material.
Canadian Patent No. 901 244 discloses a bag for insecticide powders, the bag being formed of a water-soluble film reinforced with a net of water-insoluble thermoplastic material.